This invention relates to a ventilation control apparatus for an engine room of a small-sized ship such as a motor boat, a small fishing boat etc.
Where any explosive gas such as a hydrocarbon gas is present within the engine room of a small-sized ship, an explosion sometimes takes place by, for example, sparks occurring at the start of a starting motor. It is therefore necessary to preliminarily ventilate an engine room.
A ventilating device of the engine room is arranged independently of an engine starting device as shown in a circuit arrangement (the prior art) of FIG. 1. The starting device comprises an ignition coil IG and a starter motor SM and is energized by the operation of a main switch MSW. The ventilating device or ventilating fan F is operated by a switch SW2 arranged independently of the main switch MSW. In the arrangement shown, therefore, there is a fear that the main switch MSW is operated without preliminarily operating the switch SW2 i.e. an engine is started without preliminarily ventilating the engine room. As a result, an explosion sometimes occurs due to a spark generating at the start of the starting motor. Furthermore, an unnecessary ventilation sometimes continues with the now operating fan indavertently left unattended. In the circuit arrangement of FIG. 1, V denotes a power source; Fu, a fush; SW1, a power source switch; and R1, a relay including a normally open contact RS1.